1. Field of the Invention
The present invention relates to a control assembly for manipulating the movement of an endoscopic instrument. Embodiments of the present invention relate to the control assembly and a method of manufacturing the control assembly.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
There are a number of occasions during which it is necessary to view and work on remote or inaccessible sites. For example, during a surgical operation, it is sometimes necessary to operate on organs which are within the human body. In an industrial context, certain parts of a machine can be practically inaccessible to a maintenance engineer without dismantling the machine to gain access to the parts of interest.
In the example of a surgical operation, a surgeon may wish to carry out surgery through as small an incision as possible to reduce scarring and trauma to the patient. In addition, small incisions will reduce the risk of infection and can lead to reductions in post-operative recovery times for the patient.
Thus, there is a requirement for instruments and imaging devices, with relatively small external dimensions, which can be maneuvered through small orifices to allow access to remote or inaccessible sites.
To this end, endoscopic instruments have been developed for use in surgical operations. These instruments may include, among others, endoscopes, laparoscopes, endoscopic clamps and the like.
Endoscopes comprise a rigid tubular body. The proximal end of the endoscope is attached to a camera, and the distal end is inserted into a patient. One or more optical fibers, which run through the tubular body, provide an optical link between the distal end and the proximal end of the endoscope or laparoscope. Thus, an endoscope can be used in combination with a camera to view the internal organs of a patient during surgery through a small incision. Other endoscopic instruments have a similar construction, with a tool at the distal end and an actuator at the proximal end.
Traditionally, these instruments have been held in place by an assistant who moves the instrument in response to instructions from the surgeon (who may also be manipulating a similar instrument). Recently, a number of mechanized and robotic devices have been developed to hold and maneuver endoscopes to allow the surgeon to control the camera directly, using, for example, voice commands or head movements. Similar mechanized and robotic devices have been developed for other endoscopic instruments.
One such device is described in U.S. Pat. No. 6,024,695. This document describes a device, which includes a manipulator for manipulating a surgical instrument relative to a patient's body. The manipulator can be manually or may be computer actuated. The robot is complex and is able to move in a large number of different axes, although some of these axes may be “locked” to limit the movement. In order to allow for computer actuated control of the robot a number of motors are provided.
The large number of possible axes of movement is a hindrance to the ease of operation of the robot during surgery. For example, in order to move a surgical instrument from one position to another within the patient, there are several possible movements which could achieve the same general result but which have an effect upon how future movements might be achieved.
Moreover, the positioning of the robot in one of the possible axes may have an effect upon how the robot is able to move in the other axes. For example, the document discloses a “ball and socket” joint between two parts of the robot and a sliding joint beneath the ball and socket joint. If the ball and socket joint is in a first position then movement of the sliding joint may be operative in a different direction with respect to a patient when compared with the same sliding joint when the ball and socket joint is in a second position.
In a surgical operation, if movements of an endoscopic instrument are not confocal at the incision then the patient's skin may become stretched, distorted, or torn by the laparoscope at the incision.
Thus, when controlling robots of this type, it is necessary to provide an arrangement which is capable of translating the movement of the endoscopic instrument which is desired by the operator into a complex series of movements in the various axes of movement of the robot to ensure that the desired movement is achieved in a substantially confocal manner with respect to the incision. These complex series of movements are known as compound movements and require computationally expensive kinematic calculations based upon a number of factors to determine the relative motion of each robotic joint. Factors which must be taken into consideration include the geometry of the robot, its joints and limbs, the axes in which movement is possible, and the speed at which any movement can be carried out.
Accordingly, robots for use in surgical operations are large complex devices which require significant processing power in order to operate successfully.
Similar problems exist in other fields, such as industrial applications.